The invention is directed to a device for determining whether or not a workpiece and a cutter of a horizontal milling machine or lathe are located or aligned accurately relative to each other and, if not, to what extent they are out of alignment. In particular, a fixed gauge block and pivotal angle arm are mountable on a work support or holder of a horizontal milling machine so that after an "eyeballed" rough alignment of a cutter centering plane, hereinafter referred to as a "cutter plane", with a work aligning plane, hereinafter called a "work plane", accurate alignment of the cutter and work planes is facilitated by engaging one end of the angle arm with the cutter so that the other end of the angle arm cooperates with a scale indicating an amount of misalignment.
The above cross-referenced patents each disclose a pivotal indicator arm, but none function in the manner or for the purpose of the instant invention device. Of these, the Peterson device is an indicator that is mounted in a tool-post in replacement of a tool so as to have one end thereof in engagement with a workpiece in order to move in response to variations in the work surface during work rotation and thus indicate "trueness" or the lack thereof. The Lloyd indicator is for setting the depth of cut of a fixed tool into rotatable work, while the Fortado, Jr., device is attached to a height gage or the like with the pivotal arm thereof engageable in a hole of an adjacent panel in order to indicate the height of the center of the hole relative to a datum line.